After more than a decade of research on the prognostic importance and treatment of depression after acute MI, surprisingly little is known about vulnerability to depressive disorders, the characteristics and short-term course of depression, and whether key cardiovascular risk markers covary with depression during post-MI recovery. The first 6 months after acute MI is the period of highest risk for reinfarction or mortality, yet we know little about the course and effects of depression during this interval. This study will yield a detailed account of depression and its effects during this critical period. The DISH depression interview will be administered to a series of hospitalized patients within 1 week of an acute MI; a blood sample for 5-HTTLPR genotyping will also be drawn at this time. Enrollment in the longitudinal phase will continue until 400 patients have been enrolled (100 with major depression, 100 with minor depression, 100 currently non-depressed but with a history of major depression, 100 never depressed.) The DISH will be administered in person at baseline and at 3-month and 6-month follow-up sessions, and by telephone at interim assessments (weekly through Month 3 and monthly through Month 6). Additional interview modules and questionnaires will be administered at these times to assess depression, anxiety, perceived stress, stressful life events, health behaviors, and perceived social support. At baseline, 3too, and 6mo, blood samples will be drawn for inflammatory and procoagulant markers, and 24 hr ECGs will be obtained for heart rate variability analysis. Planned analyses will identify independent predictors of post-MI depression, differentiate between rapidly remitting vs. persistent cases, and model the relationships among change over time in depression and change in cardiovascular risk markers. The effects of depression on reinfarction and survival will be examined in exploratory analyses. The results will clarify the early course of post-MI depression and the mechanisms linking depression to cardiac events, and they will inform efforts to develop more efficacious treatments.